逐级溶剂处理对子长煤有机质大分子结构的影响  

Effect of Sequential Solvent Treatment on the Macromolecular Structure of Organic Matter in Zichang Coal

作　　者：张贵雄 杨晓霞[1] 刘凯 付峰[1] ZHANG Gui-xiong;YANG Xiao-xia;LIU Kai;FU Feng(Shaanxi Key Laboratory of Chemical Reaction Engineering,YannengYanda Comprehensive Energy Industry Technology Research Institute,Yan’an University,Yan’an 716000,China)

机构地区：[1]延安大学化学与化工学院,延安大学延能延大综合能源产业技术研究院,陕西省化学反应工程重点实验室,陕西延安716000

出　　处：《光谱学与光谱分析》2021年第9期2934-2939,共6页Spectroscopy and Spectral Analysis

基　　金：中央引导地方科技发展专业技术创新平台重大研发计划项目(2019ZY-CXPT-08);国家自然科学基金项目(21663030);陕西省重点研发计划项目(2018TSCXL-NY-02-01);陕西省延安市科技稳增长专项项目(2017WZZ-10)资助。

摘　　要：从分子水平上理解低阶煤有机质大分子结构的解聚和解离是对其进行高效利用并从中获取高附加值化学品亟需解决的关键问题。为了探究煤有机质大分子结构的解聚和解离机理,借助核磁共振碳谱(^(13)C NMR)、X射线光电子能谱技术(XPS)以及热重分析(TG/DTG)对经过常温超声萃取、醇解、催化醇解逐级溶剂处理的子长低阶煤的化学结构性能进行表征。研究表明,在本实验条件下,溶剂处理降低了煤中脂肪碳比例(f_(al)),提高了芳碳比例(f_(a)),对碳、氧元素存在形态影响很大;即对大分子结构进行了不同程度的解聚和解离,使其热稳定性增加。经二硫化碳/丙酮(CS_(2)/AC)常温超声萃取,煤中的氧脂碳(f_(al)^(O1),f_(al)^(O2),f_(al)^(O3))及氧芳碳(f_(a)^(O1),f_(a)^(O2))结构增加,羰基碳(f_(a)^(C))结构降低,平均亚甲基链长(C_(n))减小,芳桥碳比例(χ_(b))降低,说明CS_(2)/AC常温超声萃取削弱并解聚了煤大分子结构中以多聚羟基为主的网状体系,C_(alk)—O,C_(ar)—O等氧桥键结构增多;而部分羰基碳结构被解离。同时,CS_(2)/AC解离了通过π—π作用等非共价键作用束缚在煤中的芳烃和脂肪烃片段。经乙醇醇解处理,煤的f_(al)降至24.89%,f_(a)升至73.05%,C_(n)降低,而甲基碳(f_(al)^(1))增加,说明醇解过程中发生了亲核取代反应,部分键能较弱的C_(alk)—O和C_(alk)—C_(alk)键断裂。继续经催化醇解作用后,煤中的氧接芳碳(f_(a)^(O3))含量明显降低,C_(n)大幅减小,说明煤中有机质进一步发生解离,部分C_(alk)—O,C_(ar)—O和C_(ar)—C_(alk)键断裂。Understanding the depolymerization and dissociation of the macromolecular structure of low-rank coal organic matter at the molecular level,is a key issue that needs to be solved urgently to efficiently use low-rank coal and obtain high value-added chemicals from it.Based on this,the Zichang low-rank coal was treated by sequential solvent treatment such as ultrasonic extraction,alcoholysis,and catalytic alcoholysis.Carbon nuclear magnetic resonance spectroscopy(^(13)C NMR),X-Ray photoelectron spectroscopy(XPS)measurements,thermogravimetric(TG)and differential thermal analysis(DTG)were used to characterize the samples.The results show that the ratio of aliphatic carbon(f_(al))in coal macromolecular structure is decreased while the aromaticity(f_(a))increased during solvent treatments.The distribution of_(a)^(C)nd O elements are influenced greatly.The macromolecular structure of coal is depolymerized and dissociated to some extent,and its thermal stability is increased.After disulfide/acetone(CS_(2)/AC)ultrasonic extraction at room temperature,the structures of oxy-aliphatic carbon(f_(al)^(O1),f_(al)^(O2),f_(al)^(O3))and oxy-aromatic carbon(f_(a)^(O1),f_(a)^(O2))in coal organic matter increase,while the proportion of carbonyl carbon(f_(a)^(C)),the average methylene chain length(C_(n))and the ratio of_(a)romatic bridge carbon(χ_(b))decrease,indicating that the network system mainly composed of polyhydroxyl in the macromolecular structure of coal is weakened and depolymerized during CS_(2)/AC extraction.The structures of C_(alk)-O,C_(ar)-O are increased.Some carbonyl carbon structures are dissociated.Some aromatic and aliphatic hydrocarbon fragments bound in coal byπ-πinteraction and other non-covalent bond interactions are dissociated by CS_(2)/AC extraction.After alcoholysis treatment,the f_(al) in coal organic matter decreases to 24.89%,and the methyl carbon(f_(al)^(1))increases,indicating that a nucleophilic substitution reaction occurs during alcoholysis.Some weaker bonds such as C_(alk)-O,C_(alk)-C_(alk) are

关 键 词：溶剂处理 解聚和解离 超声萃取 醇解 

分 类 号：TQ533.6[化学工程—煤化学工程]